POV-Ray : Newsgroups : povray.general : Media absorption problem Server Time
1 Aug 2024 04:12:32 EDT (-0400)
  Media absorption problem (Message 1 to 7 of 7)  
From: RCRuiz
Subject: Media absorption problem
Date: 5 Feb 2006 14:05:00
Message: <web.43e64c307d6d81aa11f39d970@news.povray.org>
Hi to all, I have 2 boxes like this

object {OBPlane_001 pigment { rgbt 1 }
 hollow
 interior {
  media {
   absorption 2
   density
   {
    spherical density_map
     { [0 rgb 0] [0.5 rgb 0] [0.7 rgb .5] [1 rgb 1] }
    scale 5
    warp
    { turbulence 2.0 }
    //scale 5
    }
   }
 }
}

that they intersect in some parts and give me this results

http://i10.photobucket.com/albums/a116/RCRuiz/Temporal/pov013a.jpg

When they are along they look very good. how can I fix this?

Thank you

Un Saludo


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From: Bob Hughes
Subject: Re: Media absorption problem
Date: 5 Feb 2006 15:09:11
Message: <43e65b67$1@news.povray.org>
"RCRuiz" <ram### [at] hotmailcom> wrote in message 
news:web.43e64c307d6d81aa11f39d970@news.povray.org...
> I have 2 boxes like this
> that they intersect in some parts and give me this results
>
> http://i10.photobucket.com/albums/a116/RCRuiz/Temporal/pov013a.jpg
>
> When they are along they look very good. how can I fix this?

Coincident surfaces can be a common problem, in this case the media is 
apparently affected even while the transparent boxes themselves aren't 
actually seen. Make one smaller or larger by adding scale 1.001 or scale 
0.999 and that should fix it.


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From: RCRuiz
Subject: Re: Media absorption problem
Date: 5 Feb 2006 16:30:00
Message: <web.43e66dbcefda1eb411f39d970@news.povray.org>
"Bob Hughes" <omniverse@charter%net> wrote:
> "RCRuiz" <ram### [at] hotmailcom> wrote in message
> news:web.43e64c307d6d81aa11f39d970@news.povray.org...
> > I have 2 boxes like this
> > that they intersect in some parts and give me this results
> >
> > http://i10.photobucket.com/albums/a116/RCRuiz/Temporal/pov013a.jpg
> >
> > When they are along they look very good. how can I fix this?
>
> Coincident surfaces can be a common problem, in this case the media is
> apparently affected even while the transparent boxes themselves aren't
> actually seen. Make one smaller or larger by adding scale 1.001 or scale
> 0.999 and that should fix it.

nope, it did not fix the problem but thanks . .  I just found my error , is
in max_trace_level on the global settings I put 8 and problem fix :D


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From: Bob Hughes
Subject: Re: Media absorption problem
Date: 5 Feb 2006 19:08:57
Message: <43e69399$1@news.povray.org>
"RCRuiz" <ram### [at] hotmailcom> wrote in message 
news:web.43e66dbcefda1eb411f39d970@news.povray.org...
> "Bob Hughes" <omniverse@charter%net> wrote:
>> "RCRuiz" <ram### [at] hotmailcom> wrote in message
>> news:web.43e64c307d6d81aa11f39d970@news.povray.org...
>>
>> Coincident surfaces can be a common problem, in this case the media is
>> apparently affected
>
> nope, it did not fix the problem but thanks . .  I just found my error , 
> is
> in max_trace_level on the global settings I put 8 and problem fix :D

Curiously, I tried your script by replacing the declared object with box 
{-1,1} and placed one at +y so they overlap and max_trace_level 256 can't 
remove the artifacts. Only goes away when I scale one of them to 1.001. In 
fact, if I use scale 1.0001 the shadow shows a square but the media objects 
themselves seem okay.

I also gave larger media samples value a try and that didn't change the 
original problem.

Makes me wonder if your camera is positioned in a way that makes a 
difference. I did think at first that max_trace_level could be the fault 
since it wasn't an artifact showing at any actual side where surfaces would 
be coincident but changing that hasn't done anything here.

I'm surprised about the discrepency between rendered results we have, except 
it could be computer/version/other specific. Important thing is that you 
fixed it.

Bob Hughes


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From: Jim Charter
Subject: Re: Media absorption problem
Date: 5 Feb 2006 20:26:09
Message: <43e6a5b1$1@news.povray.org>
Bob Hughes wrote:

Yes, not knowing what the object actually was I followed your lead Bob 
and tried using stacked boxes with coincident surfaces and reproduced 
artifacting similar to in his original example.  The max_trace_level had 
been set to 100, a setting I use in all my scenes by default.  But when 
I removed coincident surfaces as you'd suggested, it removed the problem.


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From: Bob Hughes
Subject: Re: Media absorption problem
Date: 5 Feb 2006 22:54:34
Message: <43e6c87a$1@news.povray.org>
"Jim Charter" <jrc### [at] msncom> wrote in message 
news:43e6a5b1$1@news.povray.org...
> Bob Hughes wrote:
>
> artifacting similar to in his original example.  The max_trace_level had 
> been set to 100, a setting I use in all my scenes by default.  But when I 
> removed coincident surfaces as you'd suggested, it removed the problem.

I'm not alone then. Thanks Jim!

Bob


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From: RCRuiz
Subject: Re: Media absorption problem
Date: 6 Feb 2006 13:05:00
Message: <web.43e78fb8efda1eb498a7cf320@news.povray.org>
"Bob Hughes" <omniverse@charter%net> wrote:
> "Jim Charter" <jrc### [at] msncom> wrote in message
> news:43e6a5b1$1@news.povray.org...
> > Bob Hughes wrote:
> >
> > artifacting similar to in his original example.  The max_trace_level had
> > been set to 100, a setting I use in all my scenes by default.  But when I
> > removed coincident surfaces as you'd suggested, it removed the problem.
>
> I'm not alone then. Thanks Jim!
>
> Bob

Hi, the thing is that I do not want to modify the size for each box. The
reason is that I'm using Blender Particles (mesh2 objects), each particle
is the same box, by using the particles it give me a nice result and I can
control the particles collision for creating obtacules on the smoke paths.
I do not know why it fix the problem with the trace level in my pc and not
in yours, that's wird :-?

Thanks


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